Natural crystalline colorant and process for production

ABSTRACT

A crystalline pigment or colorant composition having high color intensity and/or low sugar content, and methods and processes of preparation. The composition may comprise purified fruit and/or vegetable color juices.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.14/313,955 entitled “NATURAL CRYSTALLINE COLORANT AND PROCESS FORPRODUCTION” filed on Jun. 24, 2014, which is a divisional of and claimsthe benefit of U.S. application Ser. No. 13/536,578 entitled “NATURALCRYSTALLINE COLORANT AND PROCESS FOR PRODUCTION” filed on Jun. 28, 2012now U.S. Pat. No. 8,790,717, issued on Jul. 29, 2014, which claims thebenefit of and priority to U.S. Provisional Patent Application No.61/503,557 entitled “NATURAL CRYSTALLINE COLORANT AND PROCESS FORPRODUCTION” filed on Jun. 30, 2011, all of which are hereby incorporatedby reference.

FIELD

The present disclosure relates in general to purified natural colorpigments and colorants and processes for preparing and processing thepigments and colorants.

BACKGROUND

Natural colors and dyes are primarily derived from pigments that arefound in plants including fruits, flowers and vegetables. Based on theirchemical composition, natural plant-sourced pigments can be classifiedinto structural groups including, but not limited to, anthocyanins,betalains, carotenoids, curcumin, carminic acid and derivatives,chlorophylls and their derivatives, etc. Carotenoids include, but arenot limited to, β-carotene, α-carotene, apocarotenal, lycopene, bixin,norbixin, canthaxanthin, and zeaxanthin. Chlorophyll and chlorophyllinderivatives include, but are not limited to, copper complexes. Inanother non-limiting embodiment, the pigment may be complexed with ametal ion such as, but not limited to, copper.

One objective of the manufacturing industry is to concentrate thepigmented portion of plants to provide a more concentrated naturalcolorant that can be added to various food, drug, and cosmetic products.These concentrated colorants are produced by removing other compoundsthrough separation processes.

Natural colorants are often recovered from fruit and vegetable juiceswhich are high in sugar relative to the fraction of pigmented compounds.These sugar-based colors are typically concentrated to remove water andare used as a concentrate with greater than 60 percent sugar on a dryweight basis and low pigment levels. It will be appreciated that theconcentrate may have higher or lower percentage sugar on a dry weightbasis depending on the fruit or vegetable. Low color content liquids areexpensive to store (often requiring refrigeration), are subject todegradation over time, have a high calorie to color contribution ratioin food or beverage applications due to high sugar content, and/or mayimpart undesired sensory characteristics.

The industry has provided two different forms of these natural colorantsfrom fruit and vegetable juices, namely liquids and powders. Sugar-basedcolors are often difficult to dry and typically require a carrier suchas maltodextrin or micro-crystalline cellulose to compensate for thehygroscopic character of the sugar.

Further, since the liquids that are subjected to drying are typically atabout 50% w/w to 80% w/w water content, there are very few technologiesavailable to efficiently dry such products. The most common technologyavailable for drying liquids that have a low concentration of solublesolids is spray drying.

Unfortunately, spray drying has some disadvantages when it comes tohandling of the dried product. Typical problems include, but are notlimited to, significant deterioration of the product quality due to thehigh temperature and pressure that the liquid is subjected to duringdrying, the formation of amorphous particles with low bulk density dueto the rapid rate of drying in micronized droplets, and poor waterdissolution or wettability characteristics as well as hygroscopictendencies due to the presence of sugars in an amorphous rather thancrystalline state, making the powders prone to lumping or caking.Furthermore, successful spray drying of a fruit or vegetable concentratewith high sugar content typically requires the presence of a carrier,thereby weakening the color concentration and dosage efficiency of thefinished product.

Another objective of the manufacturing industry is to substantiallyreduce the sugar fraction of the standard fruit- and vegetable-basedcolor concentrates to produce a more concentrated natural color withlower caloric density that can also be dried to yield a product withimproved storage and handling characteristics. Purified colors aretypically produced by removing the non-pigment components of fruit andvegetable juices and extracts, thereby significantly enriching thematerial in the color compounds. Purified colors, containing lowconcentrations of sugar, can be dried using a broad range of dryingprocesses including spray, drum, refractive window, and freeze driers.The present process provides combinations of purification and dryingtechnology to produce concentrated natural color that can be driedwithout carriers. The concentrated natural colors described herein havea high color intensity and/or improved sensory, stability, and handlingcharacteristics relative to other dry colors known to the industry.

The foregoing examples of the related art and limitations relatedtherewith are intended to be illustrative and not exclusive. Otherlimitations of the related art will become apparent to those of skill inthe art upon a reading of the specification and a study of the drawings.

SUMMARY

The following aspects and embodiments thereof described and illustratedbelow are meant to be exemplary and illustrative, not limiting in scope.

The present disclosure relates to unique dried colorants obtained fromnatural sources including plants, such as fruits and vegetables, andalgae. In embodiments, the colorants are obtained from fruit and/orvegetable juices or juice concentrates and/or extracts. In furtherembodiments, the colorants are obtained from red grape juice and/orpurple carrot juice. The process of producing the dried colorantincludes, briefly, purifying the color pigments using variouspurification technologies and subsequently removing water using lowtemperature drying methods. This novel combination of purificationtechnologies and low temperature drying produces a unique naturalcolorant that is high in color and/or low in sugar. In embodiments, thecolorants described herein exhibit superior storage stability and/orhandling characteristics including, but not limited to density,flowability, water dispersion and/or hygroscopicity.

In one aspect, a natural colorant composition comprising a crystallinepigment or mixture of pigments derived from plants and/or algae arecontemplated. In an embodiment, the composition has a color intensitythat is higher than the color intensity of raw juice or an unpurifiedpigment or composition. In a further embodiment, the composition of theabove aspect and/or embodiment has decreased sugar on a dry weight basisas compared to raw juice or an unpurified pigment composition. Inanother embodiment, the composition of the above aspect and/orembodiments contains less than about 5-20% sugar on a dry weight basis.In a further embodiment, the composition of the above aspect and/orembodiments has a total sugar content of less than about 20% of dryweight. In yet another embodiment, the composition of the above aspectand/or embodiments has a color intensity greater than about 40,000 colorunits. In another embodiment, the pigment of the above aspect and/orembodiments is a red grape anthocyanin and the composition has a colorintensity of about 40,000-55,000 color units. In a further embodiment,the pigment of the above aspect and/or embodiments is a purple carrotanthocyanin and the composition has a color intensity of about90,000-125,000 color units. In an additional embodiment, the pigment ofthe above aspect and/or embodiments is selected from the groupconsisting of anthocyanins, carotenoids, betalains, curcumin, carminicacid, carminic acid derivatives, chlorophyll, and chlorophyllderivatives.

In another aspect, a process for producing a purified, crystallinenatural pigment is contemplated. The process comprises (a) purifying ajuice or extract containing pigments by removing at least a portion ofnon-pigment compounds to produce a purified pigment; and (b) drying thepurified pigment. In an embodiment, the purified pigment is crystallineand has an increased color intensity and/or decreased sugar content on adry weight basis compared to raw juice. In another embodiment, thepigment of the above aspect and/or embodiment is selected from the groupconsisting of anthocyanins, carotenoids, betalains, curcumin, carminicacid, carminic acid derivatives, chlorophyll, and/or chlorophyllderivatives. In a further embodiment, the step of purifying in theprocess of the above aspect and/or embodiments comprises ultrafiltrationand diafiltration across a polymeric membrane system. In yet anotherembodiment, the polymeric membrane system of the above aspect and/orembodiments comprises polyethersulfone (PES) spiral ultrafiltrationmembranes. In a further embodiment, the PES spiral ultrafiltrationmembranes of the above aspect and/or embodiments have a nominalmolecular weight cutoff of about 5000 daltons. In yet anotherembodiment, the step of purifying of the above aspect and/or embodimentscomprises circulating the juice or extract through a membrane systemcomprising (a) filtering the juice or extract through a membrane system;(b) recovering a retentate; (c) reconstituting the retentate; and (d)repeating steps (a) to (b) until the retentate reaches a desired colorstrength on a dry weight basis. In an additional embodiment, step ofpurifying of the above aspect and/or embodiments comprisesadsorption/desorption chromatography. In another embodiment, purifyingof the above aspect and/or embodiments comprises a fermentation process.In a further embodiment, purifying of the above aspect and/orembodiments comprises a subcritical or a supercritical fluid extractionprocess. In yet another embodiment, the step of drying of the aboveaspect and/or embodiments is accomplished with a refractive windowdrier. In a further embodiment, the step of drying of the above aspectand/or embodiments comprises freeze-drying. In another embodiment, theprocess of the above aspect and/or embodiments further comprises millingthe dried product.

In a further embodiment, a composition formed by the process of any ofthe above aspect or embodiments, alone or in any combination iscontemplated.

Additional embodiments of the present methods and compositions, and thelike, will be apparent from the following description, drawings,examples, and claims. As can be appreciated from the foregoing andfollowing description, each and every feature described herein, and eachand every combination of two or more of such features, is includedwithin the scope of the present disclosure provided that the featuresincluded in such a combination are not mutually inconsistent. Inaddition, any feature or combination of features may be specificallyexcluded from any embodiment of the present invention. Additionalaspects and advantages of the present invention are set forth in thefollowing description and claims, particularly when considered inconjunction with the accompanying examples and drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a flow chart illustrating an exemplary process for purifyingand drying natural fruit and vegetable based pigments, according to oneembodiment.

FIG. 2 is a flow chart illustrating an exemplary process for purifying acolorant using ultrafiltration and diafiltration, according to oneembodiment.

FIG. 3 is a flow chart illustrating an exemplary process forconcentrating purified color liquid, drying, and milling, according toone embodiment.

FIG. 4A is a side view illustration of a refractive window drier,according to one embodiment.

FIG. 4B is a cross-sectional view illustrating a refractive windowdrier, according to one embodiment.

FIG. 5 is a flow chart illustrating an exemplary process for purifyingcolor using adsorption resin separation technology, according to oneembodiment.

FIG. 6 is a flow chart illustrating an exemplary process for purifyingcolor using fermentation technology, according to one embodiment.

FIG. 7 is a flow chart illustrating an exemplary process for purifyingcolor using solvent extraction technology, according to one embodiment.

FIG. 8 is a flow chart illustrating an exemplary process for dryingpurified color using freeze-dry technology, according to one embodiment.

FIGS. 9A-9D are microscopy images at 5× magnification of purified grapepigments that are refractive window dried (FIG. 9A), freeze-dried (FIG.9B), spray dried (FIG. 9C), and drum dried (FIG. 9D).

FIGS. 10A-10D are microscopy images of FIGS. 9A-9D at 20× magnification.

DETAILED DESCRIPTION

Various aspects now will be described more fully hereinafter. Suchaspects may, however, be embodied in many different forms and should notbe construed as limited to the embodiments set forth herein; rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully convey its scope to those skilled in theart.

It will be appreciated that for simplicity and clarity of illustration,where considered appropriate, reference numerals may be repeated amongthe figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the example embodiments described herein.However, it will be understood by those of ordinary skill in the artthat the example embodiments described herein may be practiced withoutthese specific details.

The terms “colorant” and “pigment” as used herein refer to any substanceused to modify the color of an object by changing its spectraltransmittance or its spectral reflectance. “Colorant” and “pigment” asused herein generally refer to colorants and pigments obtained fromnatural sources including, but not limited to plants and algae.“Colorant” and “pigment” are used interchangeably herein.

A “concentrate” as used herein refers to a juice or extract that has hadat least some of the water removed.

“Juice” as used herein refers to the liquid obtained from a fruit,vegetable or other plant. Juice may also refer to liquid obtained fromalgae. As used herein, “juice” includes concentrate and extract. “Rawjuice” as used herein refers to juice that has not been purified.

“Increased color intensity” refers to an increase in color intensity ascompared to the color intensity of raw juice and/or unpurified pigmentcompositions.

“Decreased sugar content” refers to a decrease in sugar content on a dryweight basis as compared to raw juice and/or unpurified pigment.

Concentrations, amounts, pH values, etc., are often presented herein ina range format. The description in range format is merely forconvenience and brevity and should not be construed as an inflexiblelimitation on the scope of the invention. Accordingly, the descriptionof a range should be considered to have specifically disclosed all thepossible subranges as well as individual numerical values within thatrange. For example, description of a range such as 10-15% should beconsidered to have specifically disclosed subranges such as 10-11%,10-12%, 10-13%, 10-14%, 11-12%, 11-13%, etc.

Method of Preparing Colorants

In one aspect, a method of preparing a colorant is described. It will beappreciated that the present method may be used to prepare a pigment orcolorant and the terms are used interchangeably herein. Briefly, theprocess includes (i) optional reconstitution and pasteurization of ajuice concentrate or extract, (ii) purification of the juice concentrateor extract such as by ultrafiltration and diafiltration, (iii)concentration of the purified juice concentrate or extract such as byfalling film evaporation, (iv) drying, and (v) milling. While prior drycolorants in the food industry are spray-dried powders, the present drycolorants use low temperature drying, such as with refractive windowdrying technology or freeze drying, to produce crystalline solid coloradditives that are 100% natural, high in antioxidants, extremelyconcentrated in color, and/or completely water soluble.

FIG. 1 illustrates exemplary process steps to produce the uniquecrystalline product described above. Fruit and/or vegetable juice and/orextract 100 is typically, but not always, reconstituted (diluted) beforepurification. In one non-limiting embodiment, concentrate at about 68°Brix is reconstituted to about 18-22° Brix. In an embodiment,concentrate is reconstituted with approximately 3 parts water to onepart concentrate. Once reconstituted, the juice may be more susceptibleto fermentation from any yeast cells that might be present in thestarting material. Since the juice will remain at a low solids levelthroughout all of the subsequent liquid processing, it may optionally bepasteurized immediately to enhance microbial stability from the start ofthe process. The juice or extract may be pasteurized according tomethods known in the art. According to one non-limiting embodiment, thejuice or extract is pasteurized by heating to about 185° F. for about 30seconds and then immediately cooling to about 55° F. The juice orextract is typically, but not always, pasteurized into a jacketed tankthat becomes the feed tank for subsequent membrane filtration. All tanksused in the process may be jacketed and/or temperature controlled using,for example, food-grade propylene glycol as the refrigerant.

The juice/extract is then purified 200. By increasing the concentrationof pigment relative to sugar and organic acids, the color-enrichedliquid, under the proper drying conditions, can be converted efficientlyinto a crystalline form with superior properties, such as handlingproperties.

The juice/extract may be purified according to any suitable methodsknown in the art. In one preferred embodiment, purification 200 isachieved through the use of ultrafiltration and diafiltration acrosspolymeric membranes. Ultrafiltration (and subsequent iterations ofdiafiltration) produces a retentate that is enriched in pigments such asanthocyanin pigments or carotenoid pigments while simultaneouslydepleted in the sugars and acids that more easily permeate through themembrane. Removal of sugar increases the color concentration or colorintensity on a dry weight basis while also creating a product withsuperior storage and handling properties relative to other colorantsknown to the industry. Alternative methods of color purificationinclude, but are not limited to, column chromatography with adsorbentresins, fermentation, and extraction including, but not limited to,subcritical fluid extraction, supercritical fluid extraction, and/orsolvent extraction.

In the case of pigment purification using membrane separation, purifiedpigments, low in sugar and organic acids, are concentrated 300 byremoving water using evaporation. Depending on the membrane process, itmay be possible to dry the purified product directly withoutconcentration. Once a liquid of suitable composition and solids contenthas been prepared, the liquid is dried 400 under proper conditionseffective to create a product with the described format and properties.These conditions allow suitable rates of water removal to achievecrystallization of the solids while avoiding significant thermal damageto the color compounds.

FIG. 2 illustrates an exemplary process for purifying color pigmentsusing ultrafiltration and diafiltration to remove natural sugars andother low molecular weight dissolved solids such as organic acids fromthe retentate, according to one embodiment. In this embodiment, the feed100 to the membrane system is preferably a fruit or vegetablejuice/extract of less than about 40° Brix, and preferably between about12-22° Brix. In one embodiment, the membrane system 203 comprisespolymeric membranes as known in the art. The membrane system 203 used inone embodiment is composed of polyethersulfone (PES) with a molecularweight cutoff in the range of about 5,000-10,000 Daltons, such as thosemanufactured by Koch Membrane Systems or Hydranautics. Membranes of thistype provide rejection characteristics suitable for creating a permeatestream 205 that is enriched in sugar and acids and a retentate stream204 increasingly enriched in pigment compounds such as anthocyanins andpolyphenols relative to the concentration of sugar and acid. In anotherexemplary embodiment, a system of PES spiral ultrafiltration membraneswith a nominal molecular weight cutoff of about 5,000 Daltons is used.Ultrafiltration 202 may be performed over any operating temperature andpressure ranges that avoid damage to the membranes and providesufficient cross flow as specified by the membrane manufacturer.However, in the present embodiment, maintaining temperatures below about70° F. or more preferably below about 40° F., maintains product qualityby slowing pigment color degradation kinetics. Retentate 204 from themembrane system 203 is returned to the feed tank 201 and circulated backthrough the ultrafiltration membranes 202 until a limiting viscosity andflux is reached, typically at a retentate solids concentration of about20-25% by weight. Further purification may then continue by adding waterto the retentate 206 and concentrating again by circulating through themembrane 203 up to a limiting solids concentration. Diafiltration 206sequences are repeated until the desired pigment purity is achieved inthe retentate. The retentate, according to one embodiment, containspigment concentrations greater than about 45,000 color units on a dryweight basis compared to the base extract/juice of about 3,000 colorunits on a dry weight basis.

The diafiltration step may be modified by adding water 206 at a rateapproximately equal to the rate of permeate 205 leaving the system,thereby performing a continuous diafiltration until the desiredretentate composition is achieved.

After each concentration, retentate samples may be analyzed for residualsugar and color strength on a dry weight basis (color strength asliquid÷percent solids by weight). Once the retentate reaches a colorstrength on a dry basis that produces the product within the desiredspecifications, the product is concentrated 300. Due to the naturalvariation in the composition of the feed material for this process, theamount of diafiltration required can vary, typically from about 2-4diafiltrations.

As a non-limiting example of a batch size, a feed tank of 5,000 gallonsof reconstituted, pasteurized juice at about 18-20° Brix will becirculated through the membrane system with the retentate recycled backto the feed tank until the tank reaches a solids level of about 30° Brix(at which point the decrease in flux usually prohibits furtherconcentration). This results in approximately a fourfold reduction involume of the feed liquid, leaving about 1,500 gallons of retentate.Because this initial concentration may not increase the ratio ofpigments such as anthocyanin pigment molecules to sugar enough toachieve a targeted color strength, the retentate may undergo severaldiafiltrations to reach a sufficient dissolved solids composition.According to one embodiment, for each diafiltration, the retentate isreconstituted with a 1:1 volumetric ratio of water to concentrate andthe about 3,000 gallons of reconstituted material is circulated throughthe membrane system and concentrated back to the original retentatevolume of about 1,500 gallons.

In a non-limiting embodiment, throughout the ultrafiltration anddiafiltration process, the permeate may pass through a small surge tankattached to the membrane skid and be pumped out to a 20K gallon permeateaccumulation tank in the plant cellar where it is concentrated and usedin concentrate blends.

After achieving the desired color intensity on a dry weight basis byadjusting the ratio of pigment to sugars, membrane processing ends andthe retentate liquid may be further concentrated in solids withoutadjusting the solids composition.

Pigment purification can also be achieved using adsorption resinseparation technology. In this embodiment, shown in FIG. 5, awater-based fruit or vegetable juice/extract 100 is passed (feed liquid501) through a packed bed of adsorbent resins 502. The pigment compoundsare preferentially adsorbed on the resins relative to other dissolvedsolids such as sugar and acids 503. The adsorbed pigments aresubsequently recovered from the resin using an ethanol/water eluent 508of varying composition. The purified, pigment rich eluate 504 isdistilled 505 to recover ethanol 507. The alcohol-free, high puritypigment 506 is concentrated according to the processes noted in FIG. 3.

In another embodiment, pigment purification can be achieved usingfermentation to convert the free sugar to alcohol, and subsequentlyrecovering the alcohol using conventional distillation processes. Inthis embodiment, shown in FIG. 6, the fruit/vegetable sugar from thefruit/vegetable juice/extract 100 (feed liquid 601) is fermented toalcohol using active yeast 603 at appropriate temperature (about 50° to100° F.) in a suitable fermenter 602. It will be appreciated that othertemperature ranges may be suitable for fermentation as known to those ofskill in the art. The fermented by-product 604, comprised of about 8 to25 percent alcohol, is distilled 605 to recover the ethanol 607 leavingpurified color pigments 606. The alcohol-free liquid is subsequentlyconcentrated by removing water according to the methods outlined in FIG.3.

In yet another embodiment, pigment purification is achieved usingsupercritical fluid or solvent-solvent extraction processes. In thisembodiment, shown in FIG. 7, water-based fruit/vegetable juice/extract100 (feed liquid 701) is contacted with a non-polar, non-water miscibleextract liquid (such as hexane) or solvent 702 which preferentiallyabsorbs the color compounds. The absorption process is repeated to yieldan extract fraction rich in color compounds 705 and a fraction rich incarbohydrates and/or other non-colored components 704. A batch orcontinuous extractor 703 may be used to recover and concentrate thecolor. The extract solvent 705 is subsequently distilled 706 to recoverthe solvent for re-use 708, yielding a solvent-free, pigment-richwater-based liquid 707, which is subsequently concentrated by removingwater according to the methods outlined in FIG. 3.

FIG. 3 illustrates an exemplary process of concentrating 300 and drying400 a purified color liquid using a refractive window dryer in anexemplary embodiment. The dried crystalline material is then milled 500to produce a powder form with a consistent particle size range. Purifiedliquid can be produced using membrane filtration such asultrafiltration/diafiltration, adsorption resin, fermentation, solventextraction and/or supercritical fluid extraction technologies. Dependingon the solids content in the purified liquid, it may be necessary toconcentrate the solids to 20-35% by weight prior to drying.

Concentration 300 of the purified liquid color may be performed byfeeding the final retentate from the previous step to a falling filmevaporator, in one embodiment. Other types of evaporators, such as aforced circulation evaporator or plate evaporator may also be used.

In one non-limiting embodiment, the retentate is concentrated with afalling film evaporator prior to drying. One exemplary falling filmevaporator is a small (single effect) falling film evaporator. In oneembodiment using a falling film evaporator, a final solids content ofabout 15-20% by weight and about 25-30° Brix, the retentate iscirculated through the evaporator until the solids concentration of thefeed tank reaches about 25-30% solids by weight or about 40-45° Brix.This degree of concentration results in a volume reduction ofapproximately 45% and takes approximately 12 hours, according to oneembodiment. The resulting liquid is then ready as feed material fordrying, such as with a refractive window dryer. The liquid mayadditionally be pasteurized and packaged into mobile metal drums so thatit can be stored without spoilage and can be transported in small unitsas needed.

Because the final concentrated liquid fed to the dryer still may not beat a shelf-stable solids concentration of concentrate (which couldrequire concentration up to 68+° Brix), and is fed to the dryer at arate of about 9-12 gallons per hour with some drying embodiments, anoptional additional pasteurization step may be warranted at the end ofliquid processing. This pasteurization step may kill any yeast cellsthat may have been introduced during processing before the liquid isstored and/or gradually fed to the dryer. Any method of pasteurizationknown in the art may be used. An exemplary method of pasteurizationincludes heating the liquid about 185° F. for about 30 seconds andcooling the liquid to about 55° F. into a surge tank. From this surgetank, the liquid may be immediately pumped to a barrel filler where itis injected, without exposure to air, into bags that line the barrels(e.g., 54-gallon metal barrels). According to one embodiment, barrels offinished liquid feed material are stored at approximately 40-50° F. Thebarrels may be brought to the dryer in groups (up to four for onepallet), where they are gradually depleted one at a time.

Purifying natural pigments ensures that the final dried product exhibitssuperior shelf stability and handling characteristics including density,flowability, water dispersion, and hygroscopicity. Purified colorextracts have improved drying characteristics, and hence can be driedusing a variety of standard drying techniques including spray, drum,belt, and atmospheric/vacuum tray drying. These techniques can subjectthe pigments to excessive high temperatures or residence time, resultingin color deterioration and/or adverse sensory impact. These dryingtechniques may also produce varying crystalline morphology withassociated differences in quality or material handling characteristics.To prepare a crystalline product with superior quality, handling, and/ordissolution characteristics, the color concentrate must be dried slowly,as is the case for refractive and freeze drying, to allow formation oflarge crystal lattices, including crystallization of any residual sugar.In one embodiment, the present process uses a refractive window dryerthat significantly reduces the temperature requirements for effectivedrying and the time of exposure to elevated temperatures. Spray dryingand drum drying, in contrast, operate at higher temperatures toaccomplish drying over a very short time and leaves components in anamorphous state. Freeze drying can also be used to produce large crystallattices provided the base material is purified prior to drying.

After concentration, the liquid is dried to produce a crystalline solidpigment. In one embodiment, as shown in FIG. 3, the liquid may then beapplied to a refractive window dryer 400 to remove most of the remainingwater and produce a crystalline solid of less than about 8% moisture.The dryer 400 comprises a long tunnel, typically formed from stainlesssteel. Liquid product passes through tunnel as a thin layer spreadacross the top surface of a thin plastic conveyor belt 403. In thedrying process, hot water circulates through shallow heating traysunderneath the conveyor belt and heats the liquid layer, according toone embodiment. Thermal energy from the hot water is transmitted throughthe conveyor belt by means of conduction and radiation. In oneembodiment, the hot water is at a temperature of up to about 210° F. Itwill be appreciated that the water may be any temperature suitable toheat the liquid layer to a desired temperature. Air blowers continuouslysweep water vapor away from the thin layer surface to maximize the rateof water evaporation. The combination of evaporative cooling and limitedheat conductivity of the plastic belt keep the thin liquid layer fromreaching the temperatures of the hot water in the heating trays, whichcould negatively impact product quality. The product leaves the tunnelas a dried solid product layer which may be removed by a sharp plasticedge placed in contact with the belt at the end of the dryer. Contactwith this edge causes the layer of dried product to break off into thincrystalline pieces of varying size.

The solid product exits the dryer in forms that can be described assheets, flakes, or granules of varying particle size. These particlesmay then be milled through a screening mill 500, or other suitableparticle size reduction equipment such as an impact mill, to produceparticles in a desired size range. The desired particle size range maybe determined by specific industry applications. In the embodiment wherethe pigments are prepared as a food colorant, the desired particle sizeconsists of no less than about 90% of total particle size between about50-425 μm for purposes of optimizing handling characteristics andstandardizing bulk density. In other embodiments, about 90% of totalparticle size is less than about 100-200 μm, less than about 100-250 μm,less than about 100-300 μm, less than about 100-400 μm, less than about200-250 μm, less than about 200-300 μm, less than about 250-300 μm, lessthan about 200-400 μm, or less than about 250-400 μm.

In one embodiment, the concentrated liquid feed material 300 passesthrough a dryer such as a refractive window dryer to remove water andproduce a crystalline solid of less than about 8% moisture by weight. Inother embodiments, the crystalline solid has less than about 5-10%moisture by weight.

In one non-limiting embodiment, the present disclosure concerns uniquedry colors made from red grape juice concentrate and purple carrot juiceconcentrate. A particular embodiment is a crystalline red colorant fromgrapes with at least about 40,000 color units. In other embodiments, thecrystalline red colorant has about 40,000-55,000 color units, about42,000-55,000 color units, about 45,000-55,000 color units, about40,000-50,000 color units, about 42,000-50,000 color units, about45,000-50,000 color units. In further embodiments, the crystalline redcolorant has greater than about 40,000 color units, greater than about42,000 color units, greater than about 45,000 color units, greater thanabout 50,000 color units, or greater than about 55,000 color units.Another particular embodiment is a crystalline purple colorant fromcarrots with at least about 90,000 color units. In other embodiments,the crystalline purple colorant has about 85,000-130,000 color units,about 85,000-125,000 color units, about 90,000-130,000 color units,about 90,000-125,000 color units, about 95,000-130,000 color units,about 95,000-125,000 color units. about 100,000-130,000 color units, andabout 100,000-125,000 color units. In further embodiments, thecrystalline purple colorant has greater than about 85,000 color units,greater than about 90,000 color units, greater than about 95,000 colorunits, greater than about 100,000 color units, greater than about125,000 color units, and greater than about 130,000 color units.

FIG. 4A and FIG. 4B illustrates the side view and cross-sectional viewof an exemplary refractive window dryer 400 respectively. The dryer 400comprises a long tunnel 401, typically formed from stainless steel,suitable for rapid water evaporation. Liquid product passes throughtunnel 401 as a thin layer 402 spread across the top surface of a thinplastic conveyor belt 403.

In one non-limiting embodiment, liquid colorant is applied to the beltusing an air pump with a suction hose inserted into a feed barrel, whichpumps liquid from the barrel through a filter, such as a 75 micronin-line filter, and into a small feed balance tank. The air pump istypically controlled by the level in the feed balance tank. Valves onfeed spout(s) drain product onto an applicator tray, forming a thinlayer on the moving surface of the belt.

Hot water circulates through shallow heating trays 404 underneath theconveyor belt 403 and heats the liquid layer 402, according to oneembodiment. Thermal energy from the hot water is transmitted through theconveyor belt 403 by means of conduction and radiation. In oneembodiment, the hot water is at a temperature of up to about 210° F. Itwill be appreciated that the water may be any temperature suitable toheat the liquid layer 402 to a desired temperature.

Air blowers continuously sweep water vapor away from the thin layersurface 402 to maximize the rate of water evaporation. The combinationof evaporative cooling and limited heat conductivity of the plastic beltkeep the thin liquid layer surface 402 from reaching the temperatures ofthe hot water in the heating trays 404, which could negatively impactproduct quality.

The product leaves the tunnel 401 as a dried solid product layer 405which may be removed by a sharp plastic edge 406 placed in contact withthe belt 403 at the bullnose end of the dryer. Contact with this edgecauses the layer of dried product to break off into thin crystallinepieces of varying size. In one embodiment, the crystalline product fallsoff the end of the belt for collection. In an embodiment, plastic bagsplaced inside plastic barrels and supported by a mobile stainless steelframe are placed to collect the crystalline produce from the belt.

Soft water may be used for the water in the heating trays under the beltto avoid staining and deposits on the stainless steel. The water istypically held in tanks underneath the belt. In one embodiment, eachtank is connected to and circulated through a heat exchanger that usessteam to reach and maintain an adjustable set point temperature.

In another embodiment, the purified, liquid concentrate is dried usingvacuum, freeze-drying processes to produce a dry powder with largecrystalline structure exhibiting superior color stability, and/or colorhandling characteristics. In this embodiment, illustrated in FIG. 8, thepurified liquid is placed in a freeze dryer 801 vacuum chamber. Air andwater vapor is removed from the chamber under vacuum until the liquid inthe trays is frozen. The frozen trays are then indirectly heated usingan external source (i.e. steam, hot water, electricity) with the traysmaintained under vacuum. Residual water is sublimed from the frozenmaterial until moisture levels are below about 7 percent. The watersublimation step is performed at plate temperatures ranging from about40° C. to 100° C. for a period of about 8 to 24 hours depending on thewater content and composition of the pigment. Once the water issublimed, the trays are removed from the vacuum chamber and the drycrystals are recovered as granules of varying size. The granules aremilled through a screening mill 802, or other size reduction equipmentsuch as impact mills as known in the art, to produce particles in adesired size range 803. The milling process produces a more consistentparticle size and a higher packing density for better storage and/orshipping efficiency.

Crystalline Colorants/Pigments

In another aspect, a crystalline pigment or colorant is described.Preferably, the crystalline pigment or colorant is derived from naturalplant or algae sources. The novel combination of purificationtechnologies and drying produces a unique natural colorant, high incolor and/or low in sugar that exhibits superior shelf stability and/orhandling characteristics, including density, flowability, waterdispersion and/or less hygroscopic character. As such, the presentcrystalline pigment or colorant overcomes some of the basic problemsthat the industry has been dealing with when using dry naturalcolorants.

In embodiments, derivatives and/or modifications of the crystallinepigment are contemplated. Modifications include, but are not limited to,co-pigmentation, saponification, complexing, and/or flaking. Thepigments may be modified and then formulated into a colorantcomposition.

As seen in FIGS. 9A-9D, the present crystalline pigments are crystallinerather than amorphous. The present natural dry colorant is not spraydried and therefore is not amorphous in nature with low bulk density anddoes not require additives to enable drying or to make it lesshygroscopic. Instead, the present natural dry colorant is dried using amilder drying technique, including, but not limited to drying with arefractive window dryer, or freeze-dryer.

The crystalline colorant or pigment may be produced from any suitableplant or algae producing desired pigments. In embodiments, the pigmentsconsist of anthocyanins, carotenoids, curcumin, betalains, carminic acidand derivatives, and/or chlorophyll and derivatives. Carotenoidsinclude, but are not limited to, β-carotene, α-carotene, apocarotenal,lycopene, bixin, norbixin, canthaxanthin, and zeaxanthin. Chlorophylland chlorophyllin derivatives include, but are not limited to, coppercomplexes. In another non-limiting embodiment, the pigment may becomplexed with a metal ion such as, but not limited to, copper. Innon-limiting embodiments, the crystalline colorant or pigment isobtained from grapes or carrots. It will be appreciated that pigmentcompositions may include one or more crystalline pigments.

The present purified natural dry colorant is produced using a milderdrying technique that yields a crystalline color that isnon-hygroscopic. This purified crystalline color has excellentdispersability and dissolution characteristics due to itsnon-hygroscopic nature and does not require agglomeration andgranulation to improve dissolution characteristics.

When purifying fruit and vegetable pigment juice and extracts, thecomposition of the sugar component is reduced from about 70% to 95% on adry weight basis to about 10 to 20% on dry basis, according to oneembodiment. In other embodiments, the sugar component is reduced to lessthan 10%, to less than 15%, to less than 20%, to 15-20%, to 10-15% on adry basis. In further embodiments, crystalline pigments described hereinhave about 5-20% total sugar on a dry basis. In other embodiments,crystalline pigments have about 5-10% total sugar on a dry basis, about5-15% total sugar on a dry basis, about 10-20% total sugar on a drybasis, about 10-15% total sugar on a dry basis, or about 15-20% totalsugar on a dry basis. Reducing the concentration of sugar relative tototal dried solids also concentrates the pigmented portion to about 7 to15 times the original concentration on a dry weight basis, according toone embodiment. In embodiments, the pigmented portion is concentrated toabout 7-10 times or 10-15 times the original concentration on a dryweight basis. There are several techniques for purifying the colorants,including ultrafiltration/diafiltration, adsorption resin, solventextraction, fermentation, and super critical or sub critical fluidextractions.

As noted above, the crystalline colorant or pigments are high in color.Table 1 contrasts the color intensity of purified grape and carrotpigments to standard sugar-based natural colors. Color strengthmeasurement for Table 1 is:

$\frac{{Absorbance}\mspace{14mu}{at}\mspace{14mu} 520\mspace{14mu}{nm}\mspace{14mu}( {1\mspace{14mu}{cm}\mspace{14mu}{pathlength}} )}{{Grams}\mspace{14mu}{of}\mspace{14mu}{Sample}\mspace{14mu}{per}\mspace{14mu} 100\mspace{14mu}{ml}\mspace{14mu}{Buffer}\mspace{14mu}{Solution}\mspace{14mu}( {{pH}\mspace{14mu} 3.2} )} \times 2000.$

As shown, the typical color intensity of unpurified fruit and vegetablejuice concentrates is 2,000 to 12,000 color units. Purified pigmentsexhibited a color intensity of about 40,000 to 55,000 color units forgrape anthocyanins, and about 90,000 to 125,000 color units for purplecarrot anthocyanins. In an embodiment, the purified pigments have acolor intensity of greater than about 40,000 color units for grapeanthocyanins. In another embodiment, the purified pigments have a colorintensity of greater than about 90,000 color units for purple carrotanthocyanins. In an embodiment, the color value is equal to:

$\frac{{Absorbance}\mspace{14mu}{at}\mspace{14mu} 520\mspace{14mu}{nm}\mspace{14mu}( {1\mspace{14mu}{cm}\mspace{14mu}{pathlength}} )}{{Grams}\mspace{14mu}{of}\mspace{14mu}{Sample}\mspace{14mu}{per}\mspace{14mu} 100\mspace{14mu}{ml}\mspace{14mu}{Buffer}\mspace{14mu}{Solution}\mspace{14mu}( {{pH}\mspace{14mu} 3.2} )} \times 2000.$

In a further embodiment, the purified pigments exhibit an increasedcolor intensity as compared to raw juice and/or to unpurified pigmentsor pigment compositions. In non-limiting embodiments, increased colorintensity refers to at least about 5-200% increase in color intensity.In further embodiments, increased color intensity refers to at leastabout 5%, 10%, 20%, 25%, 50%, 75%, 100%, 150%, 200% increase in colorintensity or more.

The ranges of values for residual sugar and color intensity are providedfor illustration purposes only and represent nominal purification levelsachievable using membrane purification processes. Lower residual sugarlevels (down to less than 1 percent) are possible using additional ordifferent membrane filtration and/or different purification processesincluding fermentation, adsorption resins, and solvent extraction.

TABLE 1 Purified Pigment Color Intensity for Extracts, PurifiedConcentrate, and Purified Powder Fruit/ Color Vegetable Color (520Sugars on Strength on Pigment Type Sugar Moisture nm) Dry Basis DryBasis Grape Raw Fruit Juice 55-60% 30-40% 1,800- 90-95% 2,800-3,500Concentrate 2,200 Grape Purified Juice 3-7% 65-80% 12,000- 10-20%40,000- Concentrate 16,000 55,000 Grape Purified Pigment 10-20% 5-7%35,000- 10-20% 40,000- Crystal Powder 50,000 55,000 Carrot Raw Vegetable40-50% 30-40% 9,000- 70-80% 12,000- Juice 12,000 20,000 ConcentrateCarrot Purified Juice 3-7% 65-80% 30,000-  5-20% 90,000- Concentrate40,000 125,000 Carrot Purified Pigment  5-20% 5-7% 85,000-  5-20%90,000- Crystal Powder 120,000 125,000

As seen from Table 1, the purified pigment powder had significantlyincreased color as compared to the raw fruit extract/concentrate. Asalso seen from Table 1, the purified pigment powder had reduced sugarcontent as compared to the raw fruit extract/concentrate. The grapepigment had at least 4 times less sugar than the raw fruitextract/concentrate and the carrot pigment had at least 2.8 times lesssugar. The purified crystal red grape pigment had 13-17 times strongercolor strength on a dry basis than the unpurified grape juiceconcentrate. The purified crystal purple carrot pigment had 6-9 timesstronger color strength on a dry basis than the unpurified purple carrotjuice concentrate. In embodiments, the purified crystal pigment has 5-20times stronger color strength on a dry basis as compared to anunpurified juice concentrate. In further embodiments, the purifiedcrystal pigment has 5-10 times, 5-15 times, 10-15 times, or 10-20 timesstronger color strength on a dry basis as compared to an unpurifiedjuice concentrate.

The data shown in Table 1 reflects the use of membrane filtration topurify the natural pigment. Inherent in membrane filtration is apractical lower limit for sugar content based on the amount ofdiafiltration required and the decreasing yield of purified color withincreased diafiltration. Other purification methods, such asfermentation or adsorption resins, can potentially achieve lower sugarcontent and hence higher relative purification. It will be appreciatedthat lower sugar content and higher color purity may be obtained withother purification methods.

Table 2 summarizes the differences in physical characteristics amongrefractive window, freeze, and spray dried powders produced from thesame purified grape anthocyanin pigment. As shown, the refractive windowand freeze dried crystals exhibit markedly different photomicroscopy,particle size distribution, and particle density compared to spray driedpowder.

TABLE 2 Physical Characteristics for Purified Grape Pigments DryingMethod Unit of Refractive Parameter Measure Window Freeze SprayPhotomicroscopy Angular, Angular, Spherical, glassy, glassy glassymicro-pores Particle Size distribution^(1,2) D10 um 47 54 9 D50 um 123142 19 D90 um 277 287 38 Density Bulk (g/cm³) 0.62 to 0.70 0.28 to 0.370.24 to 0.44 Particle (g/cm³) 1.5 1.4 0.9 ¹0.5 bar dispersion pressure²The terms D10, D50, and D90 refer to the particle sizes at which 10%,50%, and 90% of the sample is smaller. Notes: The moisture content ofthe refractive window and spray dried products were 3.0% and 3.5%,respectively.

As seen from FIGS. 9A-9B and 10A-10B, refractive window and freeze driedpowders exhibit a glassy and angular crystal, reflecting relatively slowcrystal growth compared to spray dried powders. Refractive windowcrystals further exhibit micropores within the base crystal structure(FIG. 10A). The angular, glassy morphology of the refractive window andfreeze-dried crystals provide the superior physical and flowabilitycharacteristics as further discussed below.

Spray dried powder, in contrast is spherical and glassy (FIGS. 9C and10C).

The crystal size for refractive window or freeze dried powder isapproximately 7 times larger than spray dried powder produced from thesame purified grape pigments. Ninety percent of the refractive windowand freeze dried powder crystals were less than 277-287 μm whereas 90percent of the spray dried particles are less than 38 μm in diameter. Asa result of their larger average particle size, the crystalline powdersproduced by refractive window and freeze drying exhibit less dust inhandling when compared to an equivalent spray dried powder, whichresults in less airborne product loss and cleaner and safer use in amanufacturing environment.

The particle density for refractive window and freeze dried powder is 50percent greater than the value for spray dried powder: 1.5 versus 0.9grams/cm³.

Table 3 summarizes the powder flowability characteristics for purifiedgrape anthocyanin pigments dried using refractive window and spraydrying processes. As shown, purified powder produced using refractivewindow drying is less cohesive and exhibits lower wall friction andhigher air permeability compared to the spray dried version. Theseproperties result in smaller hopper outlet requirements, less steephopper angle requirements, and higher steady state discharge flow ratesrespectively.

TABLE 3 Flowability Characteristics for Purified Grape Pigments DryingMethod Parameter Unit of Measure Refractive Window Spray Cohesive Archin Mass Flow Bin¹ Continuous Flow cm 9 55 Continuous Flow after cm 12 731 day at rest Wall Friction² Continuous Flow Angle 18 11 Continuous Flowafter Angle 18 11 1 day at rest Permeability³ Steady State Flow withkg/min 700 8 2 foot diameter opening ¹Cohesive arch is the smallestoutlet diameter to avoid arching in a mass flow bin. Smaller arch sizesallow higher throughput at the same outlet size and more designflexibility. ²Wall friction is the maximum mass flow angle needed tomaintain steady flow. Larger angles allow more design flexibility.³Permeability measures the critical mass flow rate that can be sustainedwithout plugging.

Cohesive strength measures a powder's tendency to form ratholes andcohesive arches. Cohesive arch measurements determine the smallesthopper outlet size required to sustain steady-state flow withoutplugging. A smaller minimum outlet diameter is preferred since itrequires smaller transfer pipe and mixing equipment. Purified grapepigment powder produced using refractive window drying can sustainsteady flow in a cone-shaped outlet as small as 9 cm in diameter. Thesame purified pigment produced using a spray dryer requires a conediameter as large as 55 cm to sustain steady-state flow, nearly 6 timeslarger.

Wall friction angle is another measure of a powder's resistance tohopper discharge or pipe flow and susceptibility to plugging. Largerangles indicate superior flowability because mass flow can occur withhopper walls farther from vertical orientation, thereby reducing thespace footprint required to achieve a given flow rate. Purified powderproduced using refractive window drying has a conical hopper wallfriction angle of 18 degrees compared to 11 degrees for purified powderproduced using spray drying and subject to the same outlet size, wallmaterial and surface finish.

Powder permeability correlates with steady-state flow characteristics,with higher permeability able to sustain steady flow. Powders with highair permeability retain their form and sustain high flow rates throughconfined openings while powders with low permeability experiencedischarge rate limitations due to interaction with air. Flowabilitycharacteristics are quantified by determining the steady-state flow of apowder through a fixed opening. Purified powder produced usingrefractive window drying can sustain steady state flow close to 700kg/min through a 2-foot diameter conical opening compared to only 8kg/min for purified powder produced using spray drying. Similar enhancedflowability characteristics as described above for purified grapepigments are expected to hold true for other purified natural pigmentspurified using the same purification process and dried using freezedrying.

In embodiments, the pigment or colorant are formulated as a composition.The pigments or colorant may be formulated as an aqueous solution,emulsion, suspension, and/or dispersion. The pigments or pigmentcompositions are contemplated for any suitable situation of adding orenhancing color. In embodiments, the pigment or pigment compositions areused in food, drugs, and/or cosmetic applications.

EXAMPLES

The following example is illustrative in nature and is in no wayintended to be limiting.

Example 1 Crystalline Colorant Formation

A red grape juice concentrate and a purple carrot juice concentrate wereseparately reconstituted to about 18-22° Brix

The red grape juice concentrate and purple carrot juice concentrate wereseparately purified through ultrafiltration and diafiltration across aPES membrane system.

Purified red grape juice concentrate and purple carrot juice concentratewere separately concentrated using a falling film evaporator and thendried using a refractive window dryer. Purification data was measuredand the results are shown in Table 5.

TABLE 5 Crystal Purification Data Color Color Sugars Strength Sugars(520 on dry on Dry Product (Total) Fructose Glucose Sucrose Moisture nm)basis Basis Grape Red Grape 59.7 30.6 29.1 0 36.96 1,994 94.7 3,163Juice Concentrate Grape Crystal Red 8.6 4.49 4.13 0 6.14 44,040 9.246,921 Grape Grape Crystal Red 21.7 11.5 10.2 0 6.59 39,340 23.2 42,115Grape Grape Crystal Red 12.1 6.49 5.57 0 6.81 43,170 12.9 46,325 GrapeGrape Crystal Red 16.7 9.1 7.57 0 6.37 50,010 17.8 53,412 Grape CarrotPurple 46.2 4.56 5.95 35.69 35.69 9,089 71.8 14,133 Carrot JuiceConcentrate Carrot Crystal 4.7 1.75 2.5 0.489 6.3 118,600 5.1 126,574Purple Carrot Carrot Crystal 16.3 3.72 5.09 7.5 6.2 88,080 17.4 93,902Purple Carrot Carrot Crystal 14.7 1.58 2.51 10.6 7.32 92,060 15.9 99,331Purple Carrot

While a number of exemplary aspects and embodiments have been discussedabove, those of skill in the art will recognize certain modifications,permutations, additions and sub-combinations thereof. It is thereforeintended that the following appended claims and claims hereafterintroduced are interpreted to include all such modifications,permutations, additions and sub-combinations as are within their truespirit and scope.

What is claimed is:
 1. A system, comprising: a conveyor belt having atop surface, wherein the conveyor belt is configured to receive a liquidfeed on the top surface; an applicator tray at a first end of theconveyor belt that receives the liquid feed and provides the liquid feedto the top surface; one or more heating trays underneath the conveyorbelt that heats the liquid feed to facilitate production of acrystalline product from the liquid feed, wherein hot water circulatesthrough the one or more heating trays.
 2. The system of claim 1, furthercomprising an air pump; a suction hose connected to the air pump; and afeed barrel connected to the suction hose.
 3. The system of claim 2,wherein the air pump pumps a raw liquid feed from the feed barrelthrough a filter into a feed balance tank.
 4. The system of claim 3,wherein the air pump is controlled by a level of the liquid feed in thefeed balance tank.
 5. The system of claim 1, further comprising valveson one or more feed spouts that drain the liquid feed onto theapplicator tray, forming a thin layer on the moving surface of the belt.6. The system of claim 1, where the hot water is at a temperature of upto about 210° F.
 7. The system of claim 1, further comprising a tunnelthrough which the conveyor belt passes.
 8. The system of claim 1,wherein a temperature of the liquid feed is lower than a hot watertemperature.
 9. The system of claim 1, further comprising air blowersthat move water vapor away from the conveyor belt.
 10. The system ofclaim 1, further comprising a plastic edge to facilitate removing thecrystalline product from the conveyor belt.
 11. The system of claim 1,wherein the liquid feed includes a pigment selected from the groupconsisting of anthocyanins, carotenoids, betalains, curcumin, carminicacid, carminic acid derivatives, chlorophyll, and chlorophyllderivatives.
 12. The system of claim 1, further comprising a heatexchanger.